Solving the problem of food allergy – lessons from developing countries
Published online: December 17, 2019
Food allergy has become a major problem affecting up to 10% of infants and preschool children in developed countries. The exact causes of food allergies are still poorly understood. Research from around the world suggests that allergic conditions such as asthma are less common in populations living in rural environments. Regarding food allergy, very limited information is available from populations from developing countries or rural environments. Studies in such environments may provide insights for understanding the increasing prevalence of food allergy in the developed world.
In a study published in The Journal of Allergy and Clinical Immunology: In Practice, Jing Li et al evaluated more than 35,000 children aged 7-10 years to obtain reliable information on food allergies in children from China, India, and Russia. They used a standardized questionnaire along with objective assessments of sensitization by performing skin prick tests (SPT) and food-specific Immunoglobulin E (sIgE) measurements. Both urban and rural children were recruited for the study. The diagnosis of food allergy was based on a report of symptoms within 2 hours of ingestion plus the presence of sIgE and /or positive SPT to that specific food.
Food allergy was highest in children from the highly urbanized city of Hong Kong (1.50%), intermediate in Russia (0.87%), while it was very low in India (0.14%) and the rural Chinese county of Shaoguan (0.69%). Among the children recruited from Hong Kong, food allergy in children who were born and raised in Hong Kong was more than three times higher than those who were born in China and migrated to Hong Kong subsequently. Such findings highlight the importance of early environmental exposures affecting the subsequent development of food allergies. Despite the very low prevalence of food allergy, presence of IgE sensitization was very high in India and rural China. In addition to sensitization, other factors must be important to result in clinical manifestation of food allergies. Detailed studies of early environmental exposures, including dietary habits in the rural environment, may reveal the important protective factors against the development of food allergy.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.